While travelling in Central London on the Tube, you get to hear all sorts of reasons as to why trains are running late from the serious ones of ill people, to the wrong kind of snow in the tunnels causing problems.
They have managed to come up with a new one now.
While creating some new escalators at Victoria, the contractors tipped a large amount of quick drying cement down an empty shaft. Unfortunately, the voids contained a few leaks, which led to one of the main server rooms controlling the Victoria Line. Trying to control a Tube line when your server room is under a foot of concrete which is drying away isn't easy.
They worked on it overnight and its up and running again, in some part thanks to the quick solution of tipping all the sugar they could find over the concrete to stop it setting before they could get it out.
More here
and I never knew that tipping sugar on concrete stops it settling so quickly.